Remote systems, such as vehicles, have been introduced that include locomotion power derived from electricity received from an energy storage device such as a battery. For example, hybrid electric vehicles include on-board chargers that use power from vehicle braking and motors to charge the vehicles. Vehicles that are solely electric generally receive the electricity for charging the batteries from other sources. Battery electric vehicles (electric vehicles) are often proposed to be charged through some type of wired alternating current (AC) such as household or commercial AC supply sources. The wired charging connections require cables or other similar connectors that are physically connected to a power supply. Cables and similar connectors may sometimes be inconvenient or cumbersome and have other drawbacks.
Wireless charging systems that are capable of transferring power in free space (e.g., via a wireless field) to be used to charge electric vehicles may overcome some of the deficiencies of wired charging solutions. As such, wireless charging systems and methods that efficiently and safely transfer power for charging electric vehicles are desirable.
Wireless power transfer systems may utilize inductive power transfer (IPT) to transfer power between base and pickup power devices. In the context of vehicle use, the devices may be positioned on the ground and therefore subject to harsh conditions both in terms of impact and compressive forces (particularly from being driven over) and also in terms of exposure to the elements, especially water. Protection of the devices may be accomplished by using thick shielding in the construction of the device to increase mechanical strength, or by embedding the base device in the ground. However, it is generally desirable to reduce the physical footprint of the device for the purposes of both aesthetic appeal and ease of mounting. It is also desirable to minimize the degree of shielding between the base and pickup devices to reduce effects on power transfer. Further, it can be desirable to reduce the weight of the devices—particularly those mounted to vehicles.